Current Topics in Emergency Trauma Care - Trauma EXTRA Supplement (Trauma CME)

The NEXUS criteria for C-spine imaging clear patients from cervical spine fracture clinically, without imaging. The Canadian C-spine rule clinically clears cervical spine fracture without imaging. The Canadian CT Head Rule was developed to help physicians determine which patients with minor head injury need head CT imaging. The NEXUS chest decision instrument for blunt chest trauma determines which patients require chest imaging after blunt trauma. The Ottawa ankle rule shows the areas of tenderness to be evaluated in ankle trauma patients to determine the need for imaging. The ABC score for massive transfusion predicts the need for massive transfusion in trauma patients.

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1. NEXUS Criteria for C-Spine Imaging
2. Canadian C-Spine Rule
3. Canadian CT Head Injury/Trauma Rule
4. NEXUS Chest Decision Instrument for Blunt Chest Trauma
5. Ottawa Ankle Rule
6. Ottawa Knee Rule
7. ABC Score for Massive Transfusion

NEXUS Criteria for C-Spine Imaging

• Introduction
• Points & Pearls
• Why and When to Use, and Next Steps
• Calculator Review Author
• Critical Actions
• Evidence Appraisal
• Calculator Creator
• References

Introduction

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Points & Pearls

• The National Emergency X-Radiography Utilization Study (NEXUS) criteria were developed to help clinicians determine whether or not cervical spine imaging can be safely avoided in appropriate patients.
  • The validation study included a prospective, observational sample of 34,069 patients, aged 1 to 101 years, presenting to 21 trauma centers in the United States. Among the patients studied, 1.7% had clinically significant cervical spine injuries (CSIs). The NEXUS criteria were found to have sensitivity of 99.6% for ruling out CSIs.
  • The study also detected 99% of all CSIs–all but 8 of 818 patients, among whom 6 had injuries that didn’t require stabilization or specialized treatment.
  • In the study, adoption of the criteria could have decreased imaging in patients with cervical spine injuries by 12.6%.
  • Subsequent studies have found a sensitivity of 83% to 100% for CSI, with the majority of studies finding 90% to 100% sensitivity.

Points to keep in mind:

• Unlike the Canadian C-spine rule (CCR), the NEXUS criteria do not have age cutoffs and are theoretically applicable to all patients aged > 1 year. However, some literature suggests the use of caution in applying NEXUS criteria to patients aged > 65 years, as the sensitivity may be as low as 66% to 84%. In a large, retrospective trauma registry study of 231,018 patients, sensitivity was still only 94.8% (95% confidence interval, 92.1%-96.7%) (Paykin 2017).
• In the only trial to undertake a prospective head-to-head comparison of the NEXUS criteria and the CCR, the CCR was found to have superior sensitivity (99.4% vs 90.7%). However, the trial was performed by the creators of the CCR at hospitals that were involved in the initial CCR validation study (Stiell 2003). There were also post hoc “clarifications” added by the authors to the original NEXUS criteria, leading to some concerns about the generalizability of the study findings.
• There is also debate about whether x-rays of the cervical spine are sufficiently sensitive to rule out cervical spine injuries in trauma patients, and whether computed tomography (CT) is a more appropriate imaging modality in this patient population.

Why and When to Use, and Next Steps

Calculator Review Authors

Daniel Runde, MD

Critical Actions

The NEXUS criteria have been prospectively validated in the largest cohort of patients ever studied for this indication. If a patient is NEXUS criteria–negative, further imaging is likely unnecessary.

Because of concerns that the NEXUS criteria do not perform as well among patients aged > 65 years, clinicians may want to consider further imaging if there is concern about the mechanism or examination in elderly patients. Although more complicated to remember, the CCR appears to perform as well or better than NEXUS in terms of sensitivity for CSI. In cases where a patient is not ruled out by the NEXUS criteria, it may be appropriate to apply the CCR. If the patient is negative for the CCR, then further imaging is probably unnecessary; for example, patients with midline cervical spine tenderness would need imaging according to the NEXUS criteria, but potentially could be cleared by the CCR if they did not have any high-risk features and could range their necks 45 degrees to the left and right.

There is also concern that the NEXUS criteria were derived and validated in an era when plain films were much more commonly ordered to assess for cervical spine injuries. CT imaging of the cervical spine is now more common, and there is some evidence that CT may identify CSIs that would be missed by NEXUS and/or the CCR.

Evidence Appraisal

At 34,069, the number of patients enrolled in the original validation study for the NEXUS criteria was over 3.5 times greater than in the original CCR study. As applied, the rule missed 2 of the 578 patients with a clinically significant CSI, yielding a sensitivity of 99.6% (Hoffman 1998). Subsequent evaluations of the NEXUS criteria have found the sensitivity for CSI to be more variable (83%-100%), but there have been some concerns about the methodology (retrospective review) and the way the criteria were applied in several of these analyses. One trial evaluating the NEXUS criteria, in which all patients underwent CT imaging of their cervical spine, found a sensitivity of 83%, with the rule missing 2.5% (26 of 1057) of patients with fractures. Sixteen (1.5%) of these patients required prolonged time in a cervical collar, 2 (0.2%) underwent operative repair, and 1 (0.1%) had a halo placed. A retrospective analysis attempting to apply the NEXUS criteria to the validation cohort for the CCR found a sensitivity of 92.7%.

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Jerome Hoffman, MD

References

Original/Primary Reference

• Hoffman JR, Wolfson AB, Todd K, et al. Selective cervical spine radiography in blunt trauma: methodology of the National Emergency X-Radiography Utilization Study (NEXUS). Ann Emerg Med. 1998;32(4):461-469. 

Validation References

• Hoffman JR, Mower WR, Wolfson AB, et al. Validity of a set of clinical criteria to rule out injury to the cervical spine in patients with blunt trauma. National Emergency X-Radiography Utilization Study Group. N Engl J Med. 2000;343(2):94-99. 

Additional References

• Stiell IG, Clement CM, McKnight RD, et al. The Canadian C-spine rule versus the NEXUS low-risk criteria in patients with trauma. N Engl J Med. 2003;349(26):2510-2518. 
• Dickinson G, Stiell IG, Schull M, et al. Retrospective application of the NEXUS low-risk criteria for cervical spine radiography in Canadian emergency departments. Ann Emerg Med. 2004;43(4):507-514. 
• Duane TM, Mayglothling J, Wilson SP, et al. National emergency x-radiography utilization study criteria is inadequate to rule out fracture after significant blunt trauma compared with computed tomography. J Trauma. 2011;70(4):829-831. 
• Michaleff ZA, Maher CG, Verhagen AP, et al. Accuracy of the Canadian C-spine rule and NEXUS to screen for clinically important cervical spine injury in patients following blunt trauma: a systematic review. CMAJ. 2012;184(16):E867-E876.
• Goode T, Young A, Wilson SP, et al. Evaluation of cervical spine fracture in the elderly: can we trust our physical examination? Am Surg. 2014;80(2):182-184. 
• Paykin G, O'Reilly G, Ackland HM, et al. The NEXUS criteria are insufficient to exclude cervical spine fractures in older blunt trauma patients. Injury. 2017;48(5):1020-1024. 

Canadian C-Spine Rule

• Introduction
• Points & Pearls
• Why and When to Use, and Next Steps
• Calculator Review Author
• Critical Actions
• Evidence Appraisal
• Calculator Creator
• References

Introduction

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Points & Pearls

• The Canadian C-spine rule (CCR) was developed to help clinicians determine which trauma patients need cervical spine imaging.
• The CCR is highly sensitive for cervical spine injury, with most studies finding that it catches 99% to 100% of these types of injuries.
• Applying the CCR allows emergency clinicians to safely decrease the need for imaging among the trauma patient population by > 40%.
• Subsequent studies have found a sensitivity of 90% to 100% for cervical spine injury, with the majority finding 99% to 100% sensitivity.

Points to keep in mind:

• Some of the patients in the validation study did not undergo imaging if the treating clinician felt a patient was at very low risk of injury.
• The CCR is difficult to memorize due to its multiple criteria; using a smartphone app or digital reference is recommended.
• The CCR can be used in patients who are intoxicated if the patient is alert and cooperative, regardless of blood alcohol level.
• The quoted sensitivities are all for cervical spine injury. Some practice environments might be concerned with identifying any cervical spine injury, as the CCR is highly sensitive for clinically important cervical spine imaging.
• The lone trial with a sensitivity of 90% was a study in which nurses were trained to apply the CCR; retrospective review by investigators in this study found the rule was misapplied in 4 cases with obvious high-risk features. The CCR has also been successfully evaluated in paramedics.

Exclusion criteria:

• Nontrauma patients
• Glasgow coma scale score < 15
• Unstable vital signs
• Age < 16 years
• Acute paralysis
• Known vertebral disease
• Previous cervical spine surgery

Why and When to Use, and Next Steps

Calculator Review Authors

Daniel Runde, MD

Critical Actions

If a patient has any high-risk factors (eg, aged > 65 years, a defined dangerous mechanism, or paresthesias in the arms or legs) then cervical spine imaging is required. Cervical spine imaging is required if a patient has no high-risk factors but meets none of the defined low-risk criteria (eg, sitting position in the emergency department, ambulatory at any time, delayed [not immediate onset] neck pain, no midline tenderness, simple rear-end motor vehicle collision [excludes pushed into traffic, hit by bus/ large truck, rollover, or hit by high-speed vehicle]). If a patient has no high-risk factors and has neck pain, but meets even 1 low-risk factor, then it is safe to assess the patient's ability to rotate the neck 45 degrees to the left and right. If the patient can do this (even with some pain or discomfort), then no further imaging is required; if not, then cervical spine imaging is indicated.

Evidence Appraisal

In the derivation study, the authors looked at the primary endpoint of clinically significant cervical spine injury. The validation study included a convenience sample of 8924 patients, aged 16 to 64 years, who presented to 10 Canadian trauma centers with stable vital signs and a Glasgow coma scale score of 15. Among the study population, 1.7% of patients had clinically significant cervical spine injury. The CCR was found to be 100% sensitive for ruling out cervical spine injury (defined as any fracture, dislocation, or ligamentous injury). Researchers also detected 96.4% (27 of 28) cervical spine injuries that were clinically insignificant (defined as injuries that do not require stabilization or specialized treatment and are unlikely to cause any long-term problems).

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Ian Stiell, MD, MSc, FRCPC

References

Original/Primary Reference

• Stiell IG, Wells GA, Vandemheen KL, et al. The Canadian C-spine rule for radiography in alert and stable trauma patients. JAMA. 2001;286(15):1841-1848. 

Validation Reference

• Stiell IG, Clement CM, Mcknight RD, et al. The Canadian C-spine rule versus the NEXUS low-risk criteria in patients with trauma. N Engl J Med. 2003;349(26):2510-2518. 

Additional References

• Stiell IG, Wells GA, Vandemheen K, et al. Variation in emergency department use of cervical spine radiography for alert, stable trauma patients. CMAJ. 1997;156(11):1537-1544. 
• Bandiera G., Stiell IG, Wells GA, et al. The Canadian C-spine rule performs better than unstructured physician judgment. Ann Emerg. Med. 2003;42(3):395-402. 
• Dickinson G, Stiell IG, Schull M, et al. Retrospective application of the NEXUS low-risk criteria for cervical spine radiography in Canadian emergency departments. Ann. Emerg Med. 2004;43(4):507-514. 
• Vaillancourt C, Stiell IG, Beaudoin T, et al. The out-of-hospital validation of the Canadian C-Spine Rule by paramedics. Ann Emerg Med. 2009;54(5):663-671. 
• Stiell IG, Clement CM, Grimshaw J, et al. Implementation of the Canadian C-Spine Rule: prospective 12 centre cluster randomised trial. BMJ. 2009;339:b4146 
• Stiell IG, Clement CM, O'Connor A, et al. Multicentre prospective validation of use of the Canadian C-Spine Rule by triage nurses in the emergency department. CMAJ. 2010;182(11):1173-1179. 

Canadian CT Head Injury/Trauma Rule

• Introduction
• Points & Pearls
• Why and When to Use, and Next Steps
• Calculator Review Author
• Critical Actions
• Evidence Appraisal
• Calculator Creator
• References

Introduction

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Points & Pearls

• The original validation trial and multiple subsequent studies (Stiell 2001, Stiell 2005, Stiell 2010) each found the high-risk criteria of the Canadian computed tomography (CT) head rule (CCHR) to be 100% sensitive for injuries requiring neurosurgical intervention. The CCHR has an 87% to 100% sensitivity for detecting “clinically important” brain injuries that do not require neurosurgery.
• The CCHR studies excluded patients who were taking oral anticoagulants and antiplatelet agents, so no data are available for these patients.
• Patients with minimal head injury (ie, no history of loss of consciousness, amnesia, and confusion) generally do not need a CT scan. For example, patients aged > 65 years may not need a CT scan based only on age if they do not have the history mentioned above.
• When a patient fails the CCHR, clinical judgment should be used to determine if a CT scan is necessary.
• One study found the CCHR to be the most con-sistent, validated, and effective clinical decision rule for minor head injury patients (Harnan 2011).
• While there has been only 1 validation study from the United States for the CCHR, that study found the rule to be 100% sensitive for clinically important injuries and injuries requiring neurosurgery. A retrospective study in the United Kingdom found that applying the CCHR would have resulted in an increase in the number of patients undergoing CT scans in that particular practice setting. There is debate about whether the goal should be to find all intracranial injuries or to find patient-important ones that would require neurosurgical intervention.

Why and When to Use, Next Steps and Advice

Calculator Review Authors

Daniel Runde, MD

Critical Actions

The CCHR has been validated in multiple settings and has been consistently demonstrated to be 100% sensitive for detecting injuries that will require neurosurgery. Depending on practice environment, it may not be considered acceptable to miss any intracranial injuries, regardless of whether they would have required intervention.

Clinicians may want to consider applying the New Orleans criteria for head trauma, as at least 1 trial has found them to be more sensitive than the CCHR for detecting clinically significant intracranial injuries (99.4% vs 87.3%), although with markedly decreased specificity (5.6% vs 39.7%). There are other trials in which the CCHR was found to be more sensitive than the New Orleans criteria for detecting clinically important brain injuries.

Evidence Appraisal

The validation study (Stiell 2005) included a convenience sample of 2702 patients aged ≥ 16 years, who presented to 9 Canadian emergency departments with blunt head trauma resulting in witnessed loss of consciousness, disorientation, or definite amnesia and a Glasglow coma scale score of 13 to 15. Within the sample, 8.5% (231 of 2707) of the patients had a clinically important brain injury, and 1.5% (41 of 2707) of the patients had an injury that required neurosurgical intervention. In the validation trial, the CCHR was 100% sensitive for both clinically important brain injuries and injuries that required neurosurgical intervention, and was 76.3% and 50.6% specific, respectively, for these injuries.

Subsequent studies have all found the CCHR to be 100% sensitive for identifying injuries that require neurosurgical intervention. Applying the CCHR would allow clinicians to safely reduce head CT imaging by around 30% (range of 6%-40%, with most studies showing an estimated 30% reduction). In most studies, 7% to 10% of patients had positive CT scans for brain injuries that were considered “clinically important,” but typically, < 2% of patients required neurosurgical intervention. The high-risk criteria have consistently shown 100% sensitivity for ruling out the latter group.

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Ian Stiell, MD, MSc, FRCPC

References

Original/Primary Reference

Stiell IG, Wells GA, Vandemheen K, et al. The Canadian CT Head Rule for patients with minor head injury. Lancet. 2001;357(9266):1391-1396. 

Validation Reference

Stiell IG, Clement CM, Rowe BH, et al. Comparison of the Canadian CT Head Rule and the New Orleans Criteria in patients with minor head injury. JAMA. 2005;294(12):1511-1518. 

Other References

• Stiell IG, Clement CM, Grimshaw JM, et al. A prospective cluster-randomized trial to implement the Canadian CT Head Rule in emergency departments. CMAJ. 2010;182(14):1527-1532. 
• Boyle A, Santarius L, Maimaris C. Evaluation of the impact of the Canadian CT head rule on British practice. Emerg Med J. 2004;21(4):426-428. 
• Smits M, Dippel DW, de Haan GG, et al. External validation of the Canadian CT Head Rule and the New Orleans Criteria for CT scanning in patients with minor head injury. JAMA. 2005;294(12):1519-1525. 
• Harnan SE, Pickering A, Pandor A, et al. Clinical decision rules for adults with minor head injury: a systematic review. J Trauma. 2011;71(1):245-51. 
• Papa L, Stiell IG, Clement CM, et al. Performance of the Canadian CT Head Rule and the New Orleans Criteria for predicting any traumatic intracranial injury on computed tomography in a United States Level I trauma center. Acad Emerg Med. 2012;19(1):2-10. 
• Bouida W, Marghli S, Souissi S, et al. Prediction value of the Canadian CT head rule and the New Orleans criteria for positive head CT scan and acute neurosurgical procedures in minor head trauma: a multicenter external validation study. Ann Emerg Med. 2013;61(5):521-527. 
• Easter JS, Haukoos JS, Claud J, et al. Traumatic intracranial injury in intoxicated patients with minor head trauma. Acad Emerg Med. 2013;20(8):753-760.
• Schuur JD, Carney DP, Lyn ET, et al. A top-five list for emergency Medicine: a pilot project to improve the value of emergency care. JAMA Intern Med. 2014;174(4):509-515. 
• Larson DB, Johnson LW, Schnell BM, et al. National trends in CT use in the emergency department: 1995-2007. Radiology. 2011;258(1):164-73. 

NEXUS Chest Decision Instrument for Blunt Chest Trauma

• Introduction
• Points & Pearls
• Why and When to Use, and Next Steps
• Calculator Review Author
• Evidence Appraisal
• Additional Instructions
• Calculator Creator
• References
• Selected Abbreviations

Introduction

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Points & Pearls

• The National Emergency X-Radiography Utilization Study (NEXUS) chest decision instrument can rapidly identify “very low-risk” patients with blunt thoracic trauma who would not benefit from chest imaging.
• The decision instrument was developed to address concern of radiation exposure from computed tomography (CT) of the chest, which is now common in the evaluation of trauma patients. It was developed at 3 Level 1 trauma centers in a study that included > 2600 patients.
• The NEXUS chest decision instrument uses 7 criteria to identify a low-risk cohort who have a < 2% chance of having any thoracic injury and a 1% chance of having clinically significant thoracic injuries.
• It was designed to not miss any injuries but is not very specific; just because a patient does not meet low-risk criteria does not mean the patient must be imaged.

Points to keep in mind:

• One isolated rib fracture was not included as a “thoracic injury.”
• Some clinicians may disagree with the study's definitions of clinical significance.
• Clavicular tenderness is not included as “chest wall tenderness.”
• Distracting injury is vaguely defined by design, with discretion given to the clinician: “any condition thought by the [clinician] to be producing sufficient pain to distract the patient from a second (intrathoracic) injury.” From the original study (Rodriguez 2011), this includes:
  • Long bone fractures
  • Visceral injuries requiring surgical consultation
  • Large lacerations, degloving injuries, or crush injuries
  • Large burns
  • Any other injury producing acute functional impairment
  • Clinicians may also classify any injury as distracting if it is thought to have the potential to impair the patient’s ability to appreciate other injuries.
• Intoxication is also vaguely defined by design, to include:
  • A history of intoxication or recent intoxicating ingestion as reported by the patient or an observer
  • Test of bodily secretions positive for alcohol or drugs
  • Physical evidence suggesting intoxication (odor of alcohol, slurred speech, ataxia, dysmetria, or other cerebellar findings), or behavior consistent with intoxication and unexplained by medical or psychiatric illness

Why and When to Use, and Next Steps

Calculator Review Authors

Graham Walker, MD

Evidence Appraisal

The NEXUS chest decision instrument was developed by the NEXUS study group, with the goal of reducing unnecessary chest imaging in blunt trauma patients.

Derivation

The researchers first developed the rule prospectively in a study of 2628 patients at 3 trauma centers, using 12 clinical criteria. They defined significant intrathoracic injury as: pneumothorax, hemothorax, aortic or other great vessel injury, 2 or more rib fractures, ruptured diaphragm, sternal fracture, and pulmonary contusion.

Validation

The original study was subsequently validated in a study of 9905 patients. Significant intrathoracic injury was reclassified more specifically, with an expert panel weighing diagnoses to group them as major clinical significance, minor clinical significance, or no clinical significance. (See the “Definitions” section.)

To address imaging bias, the researchers at-tempted to contact all patients who did not receive imaging or had negative imaging. Among the 433 patients who were contacted, none had been diagnosed with thoracic injury on follow-up. The rule was 99.7% sensitive for major thoracic injury, 99% sensitive for major and minor thoracic injury, and 98.8% sensitive for any thoracic injury.

Definitions

Major Clinical Significance

• Aortic or great vessel injury (all are considered major)
• Ruptured diaphragm (all are considered major)
• Pneumothorax, if the patient received an evacuation procedure (chest tube or other procedure)
• Hemothorax, if the patient received a drainage procedure (chest tube or other procedure)
• Sternal fracture, if the patient received surgical intervention
• Multiple rib fracture, if the patient received surgical intervention or an epidural nerve block
• Pulmonary contusion, if the patient received mechanical ventilatory assistance (including noninvasive ventilation) of any type for management

Minor Clinical Significance

• Pneumothorax with no evacuation procedure, but with inpatient observation for > 24 hours
• Hemothorax with no drainage procedure, but with inpatient observation for > 24 hours
• Sternal fracture with no surgical intervention, but with inhospital pain management or observation for > 24 hours
• Sternal fracture with no surgical intervention and no inpatient observation, with pain managed on an outpatient basis
• Multiple rib fracture, if the patient received inhospital pain management or inpatient observation for > 24 hours
• Multiple rib fracture, with no surgical intervention and no inpatient observation, with pain managed on an outpatient basis
• Pulmonary contusion or laceration, with no mechanical ventilatory assistance but with inpatient observation for > 24 hours

No Clinical Significance

• Hemothorax with no surgical intervention and no inpatient observation, managed on an outpatient basis
• Pneumothorax with no surgical intervention and no inpatient observation, managed on an outpatient basis
• Pneumomediastinum without pneumothorax, with no inpatient observation, managed on an outpatient basis
• Pulmonary contusion or laceration with no mechanical ventilatory assistance, no surgical intervention, and no inpatient observation, managed on an outpatient basis

Additional Instructions

The NEXUS chest decision instrument for blunt chest trauma applies to patients in the emergency department who are aged ≥ 15 years and have had blunt trauma within the past 24 hours. It may be used sequentially with the NEXUS chest CT decision instrument.

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Robert Rodriguez, MD

References

Original/Primary Reference

• Rodriguez RM, Hendey GW, Mower W, et al. Derivation of a decision instrument for selective chest radiography in blunt trauma. J Trauma. 2011;7(3):549-553.

Validation References

• Rodriguez RM, Anglin D, Langdorf MI, et al. NEXUS chest: validation of a decision instrument for selective chest imaging in blunt trauma. JAMA Surg. 2013;148(10):940-946 
• Rodriguez RM, Hendey GW, Marek G, et al. A pilot study to derive clinical variables for selective chest radiography in blunt trauma patients. Ann Emerg Med. 2006;47(5):415-418. 

Ottawa Ankle Rule

• Introduction
• Points & Pearls
• Why and When to Use, Next Steps and Management
• Calculator Review Author
• Advice
• Critical Actions
• Evidence Appraisal
• Calculator Creator
• References

Introduction

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Points & Pearls

• The Ottawa ankle rule was derived to aid in the efficient use of radiography in acute ankle and midfoot injuries.
• The rule has been prospectively validated on multiple occasions in different populations and in both children and adults.
• Sensitivities for the Ottawa ankle rule range from the high 90% to 100% range for “clinically significant” ankle and midfoot fractures. This is defined as a fracture or an avulsion > 3 mm.
• Specificities for the Ottawa ankle rule are approximately 41% for the ankle and 79% for the foot, although the rule is not designed or intended to make a specific diagnosis.
• The Ottawa ankle rule is useful in ruling out fracture (high sensitivity), but does poorly at ruling in fractures (many false positives).

Why and When to Use, Next Steps and Management

Calculator Review Authors

Calvin Hwang, MD

Advice

• Tips and precautions from the creators at the University of Ottawa:
• Palpate the entire distal 6 cm of the fibula and tibia.
• Do not overlook the importance of medial malleolar tenderness.
• “Bearing weight” counts even if the patient limps.
• Use with caution in patients aged < 18 years.
• Clinical judgment should prevail if the examination is unreliable due to:
  • Intoxication
  • Uncooperative patient
  • Distracting painful injuries
  • Diminished sensation in legs
  • Gross swelling that prevents palpation of malleolar tenderness
• Written instructions should always be provided.
• Patients should be encouraged to obtain follow-up care in 5 to 7 days if pain and ability to walk do not improve.

Critical Actions

Patients who fulfill none of the Ottawa ankle rule criteria do not need an ankle or foot x-ray. Patients who fulfill either the foot or ankle criteria need an x-ray of the respective body part. Many experts would consider this score “one directional.” Because the rule is sensitive and not specific, it provides a clear guide of which patients do not need x-ray if all criteria are met; however, if a patient fails the criteria, the need for x-ray can be left to clinical judgment.

Evidence Appraisal

The original derivation study in 1992 included nonpregnant patients aged > 18 years who presented to Ottawa civic and general hospitals with a new injury < 10 days old. The initial pilot study included 155 patients, while the full-scale study included 750 patients. Any fracture that was not an avulsion of ≤ 3 mm was considered a clinically significant fracture. This resulted in the initial criteria: aged ≥ 55 years, inability to bear weight immediately after the injury and for 4 steps in the emergency department, or bone tenderness at the posterior edge or tip of either malleolus for the ankle. For the foot, criteria included pain in the midfoot and bone tenderness at the navicular bone, cuboid, or the base of the fifth metatarsal (Stiell 1992).

Further validation and refinement was completed in 1993, through a prospective study of 1032 patients in the validation and refinement phase of the study with 121 clinically significant fractures. The rules were further refined by removing the age cutoff from the ankle rule and cuboid tenderness from the foot rule, but the weight-bearing criterion was added to the foot rule. Sensitivity of the refined rules for both foot and ankle fractures was 100%, and ankle specificity increased to 41% and foot specificity to 79% (Stiell 1993).

An additional 453 patients were prospectively enrolled in the second phase of the study, where the refined rules were validated, yielding a sensitivity of 100% for both ankle and midfoot fractures.

A study of 670 children aged 2 to 16 years at 2 separate sites found that the Ottawa ankle rule again had a sensitivity of 100% for both clinically significant ankle and midfoot fractures. This study also found that ankle x-rays could have been reduced by 16% and foot x-rays by 29% if the rules were in use at the time of the study. Subsequent meta-analysis of the Ottawa ankle rule in children found 12 studies with 3130 patients and 671 fractures, with a pooled sensitivity of 98.5% and an overall reduction in x-ray utilization by 24.8%.

Calculator Creator

Ian Stiell, MD, MSc, FRCPC

References

Original/Primary Reference

• Stiell IG, Greenberg GH, McKnight RD, et al. A study to develop clinical decision rules for the use of radiography in acute ankle injuries. Ann Emerg Med. 1992;21(4):384-390. 

Validation Reference

• Stiell IG, Greenberg GH, McKnight RD, et al. Decision rules for the use of radiography in acute ankle injuries. Refinement and prospective validation. JAMA. 1993;269(9):1127-1132. 

Other References

• Stiell IG, McKnight RD, Greenberg GH, et al. Implementation of the Ottawa ankle rules. JAMA. 1994;271(11):827-832. 
• Stiell IG, Wells G, Laupacis A, et al. Multicentre trial to introduce the Ottawa ankle rules for use of radiography in acute ankle injuries. BMJ. 1995;311(7005):594-597.
• Plint AC, Bullock B, Osmond MH, et al. Validation of the Ottawa Ankle Rules in children with ankle injuries. Acad Emerg Med. 1999;6(10):1005-1009. 
• Bachmann LM, Kolb E, Koller MT, et al. Accuracy of Ottawa ankle rules to exclude fractures of the ankle and mid-foot: systematic review. BMJ. 2003;326(7386):417. 

Ottawa Knee Rule

• Introduction
• Points & Pearls
• Why and When to Use, and Next Steps
• Calculator Review Author
• Advice
• Critical Actions
• Evidence Appraisal
• Calculator Creator
• References

Introduction

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Points & Pearls

• The Ottawa knee rule was derived to aid in the efficient use of radiography in acute knee injuries.
• The rule has been prospectively validated on multiple occasions in different populations and in both children and adults.
• Numerous studies found sensitivities for the Ottawa knee rule of 98% to 100% for clinically sig-nificant knee fractures, although 1 study found a sensitivity of just 86%.
• Specificities for the Ottawa knee rule typically range from 19% to 50%, although the rule is not designed or intended for specific diagnosis.
• When the rule is used appropriately, the number of knee x-rays obtained can be reduced by 20% to 30%.
• The Ottawa knee rule is useful in ruling out fracture when negative (high sensitivity), but does poorly at ruling in fractures (many false positives).

Why and When to Use, and Next Steps

Calculator Review Authors

Calvin Hwang, MD

Advice

Tips and precautions from the creators at the University of Ottawa:

• Tenderness of the patella is significant only if it is an isolated finding.
• Use only for injuries with a duration of < 7 days.
• “Bearing weight” counts even if the patient limps.
• Clinical judgment should prevail if the examination is unreliable due to:
  • Intoxication
  • Uncooperative patient
  • Distracting painful injuries
  • Diminished sensation in legs
• Written instructions should always be provided.
• Patients should be encouraged to obtain follow-up care in 5 to 7 days if pain and ability to walk do not improve.

Critical Actions

Patients who do not have any of the Ottawa knee rule criteria present do not need an x-ray. If 1 or more of the conditions are met, then an x-ray is recommended.

Many experts would consider this score “one directional.” Because the rule is sensitive and not specific, it provides a clear guide to which patients do not need x-ray if all criteria are met; however, if a patient fails the criteria, the need for x-ray can be left to clinical judgment.

Evidence Appraisal

The original derivation study by Stiell et al was done in 1995 and included nonpregnant patients aged > 18 years who presented to Ottawa civic and general hospitals with a new injury that is < 7 days old and resulted from acute blunt trauma to the knee. The study enrolled 1054 subjects, of whom 68 had fractures, with 66 of the fractures deemed to be clinically significant (ie, not a simple avulsion fragment of < 5 mm in breadth without associated complete tendon or ligament disruption). Using recursive-partitioning techniques, the authors derived the 5 variables of the decision rule. When applied to the study population, their decision rule had sensitivity of 100% and specificity of 54% for identifying fractures and would have led to a 28% relative reduction in x-ray utilization.

Stiell et al prospectively validated their decision rule in the same patient population. They performed telephone follow-up 14 days after the patient's emergency department visit to determine the possibility of a missed fracture. Sensitivity of the decision rule was again 100%, identifying 63 clinically important fractures out of 1096 patients. Specificity was similar to the derivation study at 49%, and there was a 28% relative reduction in x-ray utilization.

Stiell et al also prospectively implemented the decision rule in different teaching and community emergency departments. They found a relative reduction in x-ray usage of 26.4%, while maintaining a sensitivity of 100% for detecting 58 knee fractures out of 3907 patients, and a specificity of 48%. Moreover, there was a significant reduction in time to discharge and total medical charges in patients who did not get an x-ray.

The Ottawa knee rule has also been prospectively validated in populations outside of Canada. Two studies, 1 in Spain and another in the United States, found that the Ottawa knee rule had a sensitivity of 100% and 98%, specificity of 52% and 19%, and a reduction in x-ray usage by 49% and 17%.

The rule was applied to children aged 2 to 16 years in a prospective, multicenter validation study in 2003. That study found the decision rule to be 100% sensitive in finding 70 fractures out of 750 children, with a specificity of 42.8% and a potential reduction in x-ray usage by 31.2%.

The Ottawa knee rule has been compared to the Pittsburgh decision rule, another well-validated clinical decision rule. A cross-sectional comparison of the 2 rules showed that both had sensitivities of 86%, although the Pittsburgh decision rule was significantly more specific. However, this study only included patients aged 18 to 79 years and excluded pediatric patients.

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Ian Stiell, MD, MSc, FRCPC

References

Original/Primary Reference

• Stiell IG, Greenberg GH, Wells GA, et al. Derivation of a decision rule for the use of radiography in acute knee injuries. Ann Emerg Med. 1995;26(10):405-413. 

Validation References

• Stiell IG, Greenberg GH, Wells GA, et al. Prospective validation of a decision rule for the use of radiography in acute knee injuries. JAMA. 1996;275(8):611-615. 
• Emparanza JI, Aginaga JR. Validation of the Ottawa knee rules. Ann Emerg Med. 2001;38(4):364-368.

Other References

• Steill IG, Wells GA, Hoag RG, et al. Implementation of the Ottawa knee rule for the use of radiography in acute knee injuries. JAMA. 1997;278(23):2075-2079. 
• Bachmann LM, Haberzeth S, Steurer J, et al. The accuracy of the Ottawa knee rule to rule out knee fractures. Ann Intern Med. 2004;140(2):121-124. 
• Nichol G, Stiell IG, Wells GA, et al. An economic analysis of the Ottawa knee rule. Ann Emerg Med. 1999;34(4):438-447. 
• Stiell IG, Wells GA, McKnight RD. Validating the “real” Ottawa knee rule. Ann Emerg Med. 1999;33(2):241-243. 
• Tigges S, Pitts S, Mukundan S Jr, et al. External validation of the Ottawa knee rules in an urban trauma center in the United States. AJR Am J Roentgenol. 1999;172(4):1069-1071. 
• Bulloch B, Neto G, Plint A, et al. Validation of the Ottawa knee rule in children: A multicenter study. Ann Emerg Med. 2003;42(7):48-55. 
• Cheung TC, Tank Y, Breederveld RS, et al. Diagnostic accuracy and reproducibility of the Ottawa knee rule vs the Pittsburgh decision rule. Am J Emerg Med. 2013;31(4):641-645. 

ABC Score for Massive Transfusion

• Introduction
• Points & Pearls
• Why and When to Use, and Next Steps
• Calculator Review Author
• Critical Actions
• Evidence Appraisal
• Calculator Creator
• References

Introduction

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Points & Pearls

• The assessment of blood consumption (ABC) score does not require laboratory results or complex calculations.
• The focused assessment with sonography in trauma (FAST) examination that is used to determine the score relies on the skill level of the clinician performing and interpreting the examination.
• The score tends to overtriage in favor of receiving massive transfusion, ensuring a low chance of withholding massive transfusion from a patient who needs it.
• While the score can help aid the decision to initiate massive transfusion, the lead clinician(s) managing the trauma should place the order, as a massive transfusion can quickly stretch the limits of the hospital blood supply.

Why and When to Use, and Next Steps

Calculator Review Authors

Cullen Clark, MD

Critical Actions

Activation of a massive transfusion protocol (MTP) triggers the release of packed red blood cells, platelets, and fresh frozen plasma at frequent intervals until the MTP is called off.

Evidence Appraisal

The original study (Nunez 2009) was a retrospective review performed at Vanderbilt University Medical Center using the institution’s trauma registry. The study population was derived from all trauma patients (n = 596) admitted to the hospital over the course of a year. Patients included were Level I trauma activations transported directly from the scene who received any blood transfusion while admitted. The ABC score was created by the trauma faculty based on clinical experience, and logistic regression modeling was used to determine the odds ratio of requiring MTP for each parameter of the score.

Of the total cohort, 76 patients (12%) required massive transfusion in the first 24 hours. Based on the number of patients who received massive transfusion and were identified using the ABC score, researchers found the best cutoff to be a score ≥ 2, giving a sensitivity of 75% and specificity of 86%. Compared with the Trauma Associated Severe Hemorrhage scoring system and the McLaughlin score using the same dataset, the ABC score was shown to be the most accurate in predicting need for MTP.

The validation study (Cotton 2010) was a retrospective review using trauma databases from 3 institutions: Vanderbilt University Medical Center, Johns Hopkins Hospital, and Parkland Memorial Hospital. The inclusion and exclusion criteria were the same as the original study. The study population was again derived from trauma patients admitted to 1 of the 3 hospitals over the course of a year. The sample size of the study was 1604, including 586 patients from the original study. There was signifi-cant variation in demographics between the centers involved, but the massive transfusion rate in the first 24 hours of admission was similar (approximately 15%) for each hospital. There was little variability between each institution’s cohort in the percentage of patients correctly classified as meeting the ABC score cutoff for MTP, among those who received massive transfusions. For each institution, sensitivity ranged from 76% to 90% and specificity ranged from 67% to 87%. Negative predictive value was 97% and positive predictive value was 55%.

The validation study also measured the accuracy of the ABC score at predicting need for massive transfusion in the first 6 hours of admission. Sensitivity was 87% and specificity was 82% with slightly higher negative predictive value (98%) and lower positive predictive value (55%) compared to prediction of massive transfusion need in the first 24 hours.

The major limitation to both studies was their retrospective nature. A prospective trial is ongoing. The study shows a novel means of quickly predicting the need for massive transfusion based on objective measures. While there is good data showing that early activation of MTP improves survival rates in severely injured trauma patients, a prospective study will be necessary to determine if utilization of the ABC score improves patient outcomes.

Calculator Creator

Bryan Cotton, MD

References

Original/Primary Reference

• Nunez TC, Voskresensky IV, Dossett, LA, et al. Early prediction of massive transfusion in trauma: simple as ABC (assessment of blood consumption)? J Trauma. 2009;66(2):346-352. 

Validation References

• Cotton BA, Dossett LA, Haut ER, et al. Multicenter validation of a simplified score to predict massive transfusion in trauma. J Trauma. 2010;69(Suppl 1):S33-S39. 

Additional References

• Holcomb JB, Tilley BC, Baraniuk S, et al. Transfusion of plasma, platelets, and red blood cells in a 1:1:1 vs a 1:1:2 ratio and mortality in patients with severe trauma: the PROPPR randomized clinical trial. JAMA. 2015;313(5):471-482.